Cell surface receptors called integrins mediate cell adhesions and can regulate migration and survival of tumour cells. Expressions of specific integrins help to detect if the primary tumour has invaded i.e. becomes metastatic which can help in developing new antibodies and inhibitors and modulate them. Methods: Reverse transcription PCR (RT-PCR) has been used to test whether the integrins (αV, αIIb, β3) expression of Breast tumour cell lines (MDA-MB-231, MDA-MB-435 and MCF-7) are characterised at the mRNA level. Each integrin expression sample was then visualised by agarose gel electrophoresis. Different cDNA concentration of MDA-MB-231 cell line was used to illustrate if the expression of β3 integrin of the same cell line will increase. Results: Each breast cell line has different expression of integrins. However; all breast tumour cell lines have expressed the αV integrin. Whereas, MDA-MB-231 has showed increased expression of both αV and β3 integrins in MDA-MB-231 cell line.Similary, β3 integrin has showed significant expression and density in MDA-MB-435 cell line. The expression of integrin β3 in MDA-MB-231 cell line showed increased in its level when the concentration of cDNA was increased. Conclusion: These results demonstrate that breast tumour cell lines expressed both αV and β3 integrins in both MDA-MB-231 and MDA-MB-435 cell lines.MCF-7 expressed αV and αIIb integrins which means that the expression of different integrins in breast tumour cell lines are characterised and that will help in developing integrins inhibitors that can block tumour growth and metastatic of breast cancer.
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Breast cancer is the most common cancer of females which affects 1 in 9 women in the UK. Metastasis of breast tumour cells and their growth at distal regions is the main cause of death in breast cancer patients.
Metastasis or tumour invasion is when the neoplastic cells are released from its primary site and migrated into other tissue by moving into the lymphatic or vasculature. Metastasis is associated with alteration in integrins expression (Albelda, 1993).
Integrins are heterodimeric cell surface receptors found spanning the lipid bilayer (Hynes, 1987),consisting of 18α and 8β heterocomplexes integral membrane glycoproteins subunits (Desgrosellier and Cheresh, 2010) which play key roles in regulating the migration and survival of both normal and tumour cell. They are involved in mediating cell adhesions by cell to extracellular matrix (ECM) or cell to cell interactions. Extracellular long domains that are components of integral membrane glycoproteins contain the ligand binding regions. When ligand binds to integrins ,receptors will clustered and conformational changes will occur in the α and β chains which will then produce signalling (Mizejewski, 1999).Activated growth factor receptors and cytokines help integrins promotes intracellular signalling which are important in migration and invasion of tumour cells (Desgrosellier and Cheresh, 2010).For example, αVβ3 integrin (vitronectin receptor) which is expressed in breast cancer promotes the activation of pro-apoptotic caspases when crosstalk with fibroblast growth factor receptor ,FGFR (Desgrosellier and Cheresh, 2010). Also, transforming growth factor β (TGFβ) can be altered by integrin signalling for example, integrin αVβ3 induces epithelial mesenchymal transformation in breast tumour cells with the cooperation of TGFβ (Galliher and Schiemann, 2006).
Most of integrins on cell surface receptors are inactively expressed in normal tissues which means they do not produce signals or bind to ligand (Hynes, 2002). But in case of cancer, some integrins are significantly expressed or altered for example; αVβ3 integrin is correlated with the invasiveness and disease progression in breast cancer.
The α2β1 integrin is significantly expressed in normal epithelium of breast tissue, whereas in metastatic breast cancer ,the expression of this receptor was reduced (Mizejewski, 1999).
Integrins play key roles in regulating the migration and survival of both normal and tumour cells (Albelda, 1993) ,i.e. normal cell survival and apoptosis are regulated through the ligated that promotes survival and un-ligated integrins that mediates apoptosis respectively (Desgrosellier and Cheresh, 2010).When both nuclear factor-ÐºB and/or the activity of P13K-AKT are increased. The activity of p53 is decreased and that will initiate pathways of pro-survival. The apoptosis pathway is initiated by the un-ligated integrins through the cleavage of caspase-8.Figure 1 illustrates these pathways that regulate cell death and survival by integrins which has been taken from (Desgrosellier and Cheresh, 2010).
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In case of metastasis of breast cancer cells, tumour cells will either lose or increase its' ability to adhere to adjacent cells or to the extracellular matrix. This means that the activity of p53 will increase whereas the activity of both NF-ÐºB and P13K-AKT will decreased. This will promote survival and proliferation of tumour cells. That is why mutant p53 (guardian of the genome) act as a tumour suppressor to detect tumour cells(Levine and Oren, 2009). Whereas apoptosis pathway will be blocked to prevent cells from dying i.e. the αVβ3 integrin will protect cells from apoptosis through the phosphorylation of Ser338 and Ser339 of RAF.
Furthermore, Integrins can regulate the angiogenesis process, as the metastasis of breast cancer promotes the formation of blood vessels and growth of tumours (Kumar et al., 2001). The αv integrin subunits can heterodimerize with beta subunits β3 to form specific ligand binding site (Garmy-Susini and Varner, 2008).Regulation of angiogenesis was first shown by the αVβ3 integrin (Cheresh, 1987).It works as an angiogenic switch by Triggering an apoptotic response when the appropriate ligand is absent in αVβ3 expressing endothelial cells or enhancing the growth of vessels when ligated (Sloan et al., 2006).
This explains that integrins play critical role in tumour invasiveness. And their inhibitors or antagonists could be a significant target for blocking the metastasis of tumour cells.
Integrin function can be inhibited by potent inhibitors of platelet aggregation which known as dis-integrin.These disintegrins contains RGD (Arginine-glycine-aspartic acid) cell attachment recognition sequence which works by blocking platelet aggregation and inhibits adhesion of other integrins (αVβ3) that are RGD-dependent (Garmy-Susini and Varner, 2008).
RGD sequence (rich in cysteine) is an integrin binding site which found in vitronectin receptor and other extracellular matrix proteins such as fibronectin, fibrinogen and laminin. The integrins (αV, αIIb and β3) are RGD receptors(Hynes, 2002). Since vitronectin receptor αVβ3 contains this sequence, it has the ability to inhibit cell adhesion to specific extracellular proteins and since the expression of this integrin is associated with the invasiveness of tumour cells, blocking this integrin is a target for breast cancer therapeutics.
The first integrin antagonist developed was the monoclonal antibody LM609 which helped in blocking the expression of αVβ3 integrin. It significantly showed reduced in growth of human breast cancer and angiogenesis in pre-clinical trials (Brooks et al., 1995).Whereas the first anti (αVβ3) integrin that was used in phase1 clinical trials with its precursor vitaxin is etaracizumab and has showed an apoptosis effect (Gutheil et al., 2000).
Another previous study has showed that SCH221153 which is an RGD peptidomimetic potentially inhibits the αVβ3 integrin (Kumar et al., 2001).Another study has showed that ,The αVβ3 integrin antagonist (SB 265123) which is nonpeptide has significant effect in reducing the invasiveness of MDA-MB-231 and MDA-Mb-435 breast tumour cell lines (Bartsch et al., 2003).A study has showed that PSK1404, an αVβ3 integrin antagonist have significant effect in blocking the formation of breast cancer bone metastasis by effect on cancer cells (Zhao et al., 2007).
Most of the inhibitors and antagonist mentioned above blocks the αVβ3 integrin which means that αVβ3 is a dimer. Most of the breast cancer cell lines express the αV and β3 integrin but to block these integrins, αV should heterodimerize with β3 so the anti-integrin can inhibit the metastasis of tumour cells.
Reverse transcription PCR (RT-PCR) has been used to examine if the expression of αV, αIIb and β3 integrins in a panel of different breast cancer cell lines (MDA-MB-231, MDA-MB-435 and MCF-7) are characterised through the use of agarose gel electrophoresis to visualise the expression of these integrins which will promote modulating and developing new inhibitors that help blocking the metastasis and tumour growth of breast cancer.
2.0 Materials and methods:-
Breast tumour cell pellets were prepared at Institute of Cancer Therapeutics; the following cell lines [MDA-MB-231, MDA-MB-435, and MCF-7] were used.
RNA was obtained and extracted using the Rneasy Mini Kit by Qiagen inc. (Crawley, UK).Defrosted cell pellets [MCF-7/MDA-MB-231/MDA-MB-435] were resuspended in 1ml phosphate buffered saline solution (PBS) and 500µl was then added into two of 1.5 ml eppendorf tubes.
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Phosphate buffered saline solution (PBS) was prepared by dissolving 8g sodium chloride (NaCL)-(Sigma),0.2g potassium chloride (KCL)-(Sigma Ultra),1.44g sodium phosphate dibasic (Naâ‚‚HPOâ‚„)-(Sigma) and 0.24g potassium phosphate-menobasic :anhydrous (KHâ‚‚POâ‚„)-(Sigma) in 800ml of distilled water (dHâ‚‚O).pH was adjusted to 7.4 by hydrochloric acid (HCL).Distilled water (dHâ‚‚O) was added to 1L and autoclaved by Astell autoclaving machine.
Cell pellet was centrifuged by [Eppendorf- Mini Spin] for 4 minutes at 4400rpm.Supernatant was then removed, one of the cell pellets in 1.5ml eppendorf tubes was kept at -20ËšC prior to use. The other one was resuspended in 600µl buffer RLT. Pipette was then used to pipet the lysate into a qiashredder (Qiagen) and was centrifuged [Eppendorf- Mini Spin] for 2 minutes at 10.000rpm.Caps of Qiashredder (Qiagen) was discarded and 600µl of 70% ethanol was added to an RNeasy spin column (Qiagen) and centrifuged [Mini Spin Eppendorf] for 15 seconds at 10,000rpm.Ethanol helps RNA to bind to silica matrix in the spin column. The flow was discarded and 700µl of buffer RW1 was added to the column, centrifuged [Eppendorf- Mini spin] for 15 seconds at 10,000 rpm, the flow was discarded. RPE buffer (500µl) was twice added to the column consecutively and centrifuged [Eppendorf- Mini spin], firstly for 15 seconds at 10,000 rpm and secondly for 2 minutes at 10,000rpm, the flow was then discarded each time after the column is centrifuged. RNeasy spin column (Qiagen) was placed in 2ml eppendorf tubes (Qiagen) and was centrifuged [Eppendorf- Mini spin] for 1 minute at 10,000 rpm.RNeasy column (Qiagen) was placed in a 1.5ml eppendorf and 40 µl of sterile distilled water (dHâ‚‚O) was added and centrifuged [Eppendorf- Mini spin] for 1 minute at 10,000 rpm.
The concentration of RNA was determined using a spectrophotometer (Cary 50bio UV-visible, Varian)machine to measure the absorbance at 260 nm and 280nm (Aâ‚‚â‚†â‚€/Aâ‚‚â‚ˆâ‚€).RNase-free cuvettes were used to measure RNA samples.
Distilled water -dHâ‚‚O(500µl) was used as a control for the absorption experiment reading followed by 495µl of water +5µl of RNA for RNA determination through measuring the absorbance by spectrophotometer machine(Varian).
RNA concentration was calculated as follows:
-10D =40µg/ml for RNA
-Volume of RNA sample = 100µl
RNA concentration (µg/µl) = Aâ‚‚â‚†â‚€ - 40µg/ml - dilution (100µl) /1000
-Reverse Transcription (cDNA preparation)
Reverse transcription was carried out in 0.5ml PCR tubes using 2µg of total RNA, 1µl of Oligo dTâ‚â‚ˆ primer (0.5 µg/µl) (Qiagen) and sterile distilled water (dHâ‚‚O) to make total of 12µl.After 5 minutes incubation at 70°C by PCR [pettier thermal cycler] machine, 7µl from the following master mix (4µl of 5x reaction buffer, 1µl Ribonuclease inhibitor (20U/µl) and 2µl of 10mM dNTP was added and incubated for 5 minutes at 37°C by PCR [pettier thermal cycler] machine. Revert Aid H Minus RT (200U/µl)-(Fermentas) of 1µl volume was added and incubated for 60 minutes at 42°C by PCR [pettier thermal cycler] machine. The enzymes were inactivated by PCR [pettier thermal cycler] machine by heating at 70°C for 10 minutes. The cDNA was chilled on ice and 60µl of sterile distilled water (dHâ‚‚O) was added. Samples were stored at -20°C until required for analysis.
-Polymerase Chain Reaction
-The Integrin master mix was prepared. All volumes were multiplied by the number of reactions for each integrin primer pair and each cell line,18µl of the following master mix (2µl cDNA, 2µl of 10x PCR buffer, 4µl of 5x solution Q, 0.4µl of 10mM dNTP, 0.2µl Taq polymerase (5U/µl) and 9.4µl of distilled water -dHâ‚‚O) was added to 0.5ml PCR tubes followed by 1µl of forward primer (10pmol/µl) and 1µl of reverse primer (10pmol/µl).This master mix was incubated by PCR [pettier thermal cycler] machine at the following conditions.
Integrin: 94°C- 3 minutes (94°C- 30 sec; 58°C -30sec; 72°C -45sec)-22,72°C- 5 minutes.
-The GAPDH master mix was prepared however. All volumes were multiplied by the number of reactions for each GAPDH primer and each cell line, 18µl of the following master mix (2µl of 10x PCR buffer, 0.4µl of 10mM dNTP, 1µl Forward primer (10pmol/µl), 1µl Reverse primer (10pmol/µl), 0.2µl Taq polymerase (5U/µl) and 13.4µl of distilled water -dHâ‚‚O) was added to 0.5ml PCR tube followed by 2µl of cDNA. This master mix was incubated by PCR [pettier thermal cycler] machine at the following conditions.
GAPDH: 94°C- 3 minutes (94°C- 30 sec; 60°C- 30sec; 72°C -45sec) -22,72°C 5 minutes.
Integrin primer sequences
Forward : 5'-CTGGAAGAGGCTGGGGAGTC-3'
Reverse : 5'-GCATAGGGGAGGGAGGACAC-3'
Forward : 5'-CGGGACCATCTCATCACTAAG-3'
Reverse : 5'-TCTTGTTCTTCTTGAGGTGGC-3'
Forward : 5'-GGGGACTGCCTGTGTGACTC-3'
Reverse : 5'-CTTTTCGGTCGTGGATGGTG-3'
-Agarose gel electrophoresis.
Samples were analysed by agarose gel electrophoresis. The gel was carried out using 300ml of 1xTAE. Agarose-3g (Sigma) Poole, UK was placed in a 500ml Erlenmeyer flask and weighed off by (AND-EK-300i). Agarose (Sigma) was dissolved by heating the solution in a (Panasonic microwave, 800W) for approximately 2 minutes until the liquid was clear. The gel was allowed to cool before adding 5µl of Ethidium Bromide (sigma) and then poured into the gel tray until it set. Samples were analysed by agarose gel electrophoresis (Bio-RAD) SUB-cell GT.
Ethylenediaminetetraacetic acid disodium salt dihydrate -EDTA (PH8.0)(Sigma) was prepared when 186.1g of EDTA was added to 800 ml of distilled water (dHâ‚‚O).pH was adjusted to 8.0 with NaOH (˜20g NAOH pellets-sigma) while it was stirred on a magnetic stirrer. For the preparation of 50ml of EDTA (PH 8.0), 9.305 g EDTA and 1g of (NaOH pellets -Sigma) were needed. Preparation of 50 x TAE (1L) was carried out using 242g Tris base(Trizma base minimum 99.9% titration-sigma),57.1ml glacial acetic acid (Fischer scientific LTD)and 100ml 0.5 M EDTA (PH8.0).
DNA loading buffer was prepared by using 30% (w/v) sucrose (Sigma) and 0.35 %( w/v) orange G (Sigma). In this experiment 10ml of DNA loading buffer was needed so 3g of sucrose (Sigma) and 0.035g of orange G (Sigma) were used. It was made up to 10ml with distilled water (dHâ‚‚O).The gel was scanned by (Bio-RA) molecular imager FX using the Quantity one software.
Integrins (β3-αIIb-αV) of various types of breast cancer cell lines have been analysed by PCR to characterise their expression at the mRNA level.
RNA concentration was determined using a spectrophotometer prior to reverse transcription.RNA concentration ratio Aâ‚‚â‚†â‚€/Aâ‚‚â‚ˆâ‚€ should be around (1.7-2.0).If the ratio was more than 2.0, it indicates contamination of RNA or DNA however, if it was less than 1.7, it indicates protein or other contamination. The ratio for the three breast cancer cell lines were approximately around 2.0.
Table 1: RNA concentration of Breast tumour cell pellets.
Cell pellets sample
Agarose gel electrophoresis
The integrins expression were analysed by agarose gel electrophoresis. Figure 2 illustrates the expression of integrins in three types of breast cancer cell lines. There are however, common patterns of expression. All breast cancer cell lines expressed the αV and β3 subunit except for MCF-7 which expressed αV and a very low level of αIIb (figure 2B).GAPDH band was strongly expressed, as the size of the band was same with all the three breast cancer cell line (GAPDH was approximately 650bp).According to the product sizes of the integrins, αV product was 488bp and β3 was approximately 544bp for the MDA-MB-435 cell line (figure 2C).But for MDA-MB-231 cell line, the migration of the bands gave higher product sizes for the integrins, for instanse,αV and β3 were approximately 590bp and 670bp respectively which means higher than the sizes of integrins products should be (figure 2A).Finally, the size of αV integrin product was approximately 488bp according to (figure 2B).
Figure 2 illustrates the density of the integrins, PCR products that have been expressed. There was no big variation for the high Density of αV and β3 integrins in MDA-MB-231 cell line (figure 3A).In contrast with (figure3B), the density was low for both αV and αIIb in MCF-7 cell line. The density of β3 integrin was very high in MDA-MB-435 comparing with other breast cell lines, however for αv; the density was lower than that in MDA-MB-231 (Figure3C-3A).
Different volumes of cDNA have been used for β3 integrin of MDA-MB-231 cell line (figure 4).The expression of the bands was getting brightener as the volume of cDNA was increased. There was very low expression of 0.1µl which was difficult to be recognised (figure 4A). The density for the different volumes of cDNA was in the linear range; moreover, the relationship between the densities of β3 integrin was proportional to the various volumes of cDNA for β3 integrin of MDA-MB-231 cell line (figure 4B).
MDA-MB-231-with indications.jpgMCF-7-with indications.jpg
Figure2: Agarose gel electrophoresis of three different integrins cDNA (αV,αIIb and β3)in three breast cancercell lines.The gel was scanned and integrins were visulised by Ethidium Bromide.GABDH (house keeping gene)was used as a control at a concentration of 12µl.(A)MDA-MB-231. (B) MCF-7. (C) MDA-MB-435.
Figure 3: Ratio of intensity integrin band/intensity GABDH band for three of breast cancer cell lines. (A) MDA-MB-231. (B) MCF-7(C) MDA-MB-43
mda-mb-231-beta 3 with indications.jpg
MDA-MB-231-beta 3 graph.jpg
Figure 4: (A). Expression of beta 3 integrin of MDA-MB-231 by Agarose gel electrophoresis. Different volumes of cDNA have been used for the beta 3 integrin.GAPDH was used as a control and the band have been visualised by Ethedium Bromide. (B). Different volumes of cDNA for the beta 3 integrin have been plotted against density CNT/mm² in this graph.
This presented study has illustrated that various integrin expression in a panel of human breast tumour cell lines (MDA-MB-231,MDA-MB-435 and MCF-7) at the mRNA level was characterised and expressed by RT-PCR.It demonstrated elevated and highly variable integrins (αV,αIIb,β3) expression when visualised by agarose gel electrophoresis.
From the results, it is clear that MDA-MB-231 cell line has expressed both αV and β3 integrins (figure 2A).The expression of both these integrins was approximately the same. Whereas in MDA-MB-435, β3 integrin has significantly expressed (figure 2C) and the density of β3 was very high (figure 3C).The αV integrin was also expressed in MDA-MB-435 cell line. It is also clear that MCF-7 cell line has expressed the αV integrin but there was very poor level of αIIb expression. Moreover, MCF-7 cell line was negative for β3 integrin which make it different from the MDA-MB-231 and MDA-MB-435 cell lines. Both these cell lines were negative for αIIb integrin.
These results show and mean that different breast tumour cell lines express different integrins i.e. different from normal breast tissue which can help and detect the invasiveness and migration of tumour cells. Moreover, the αV integrin was expressed and active in all the three breast tumour cell lines. Comparing these results with normal breast epithelium,α2β1 was significantly expressed with no expression of αV or β3 integrins or i.e. the expression of αVβ3 was reduced (Desgrosellier and Cheresh, 2010).According to (figure 4),it was very clear that expression of β3 was significantly increased when cDNA concentration of MDA-MB-231 cell line was increased and the results showed the same with the density of β3 expression. The graph was linear and that means that the more cDNA presented in a tumour cell line the more the integrin will be expressed and this indicates that malignant tumours highly express integrins than the benign ones because in case of malignant tumours i.e. metastatic tumours, there will be more tumour cells (more DNA).
These results supported previous studies. For example , MDA-MB-231 support other work: It is the only breast cancer cell line that express this receptor comparing with the other breast cancer cell lines which express other integrins such as the αV and β1 subunit (Meyer et al., 1998).MDA-MB-435 cell line has also significantly expressed the αVβ3 vitronectin receptor and was negative for the integrin αIIb (figure 2C).The metastatic phenotype in the MDA-MB-435 human breast cancer cell line correlates with the expression of activated αVβ3 integrin. In addition to that, there is evidence, that the integrin αVβ3 expression is required for successful breast cancer metastasis.(Felding-Habermann et al., 2001).MCF-7 has also expressed the αV integrin but there was no clear expressed bands for αIIb. One of the Reverse transcription PCR study has documented that MCF-7 cell line expressed both αV and significant expression of αIIb which make it different from MDA-MB-231 and MDA-MB-435 breast tumour cell lines (Chen et al., 1997). Furthermore, MCF-7 was negative for β3 as there was no appeared expression (figure 2B).Another study has showed that MCF-7 cell line was negative for αVβ3 integrin (Beauvais et al., 2004).However, the results in this study demonstrated that there was different patterns of integrins densities for each of the three breast tumour cell lines. The density of both αV and β3 integrins in MDA-MB-231 cell line illustrates that this breast tumour cell line significantly expressed the αVβ3 integrin (figure 3A). Whereas the density of β3 integrin was higher than the density of αV integrin in MDA-MB-435.it means that the MDA-MB-435 breast tumour cell line might significantly expressed β3 (figure 3B).
The density of αV integrin was higher (double) than αIIb integrin for MCF-7 breast tumour cell line. In this case and according to the Reverse transcription PCR study that has been mentioned above, density of αIIb integrin should be higher than αV integrin as αIIb was significantly expressed in MCF-7 breast tumour cell line which means that these results do not agree with previous studies (Chen et al., 1997).There are factors which could be the reason that the results of MCF-7 was different. It could be from the sterilisation. For example, the equipment that has been used in this experiment was not sterile (Tips for pipette or the PCR tubes) that might led to contamination or it could be from the inaccuracy of using the pipettes to measure the right amounts or concentrations. Moreover, it might be because MCF-7 cell line was taken from different women (ethics, age or the extent of the invasiveness of tumour cells).
Metastasis of breast tumours to bone is correlated with tumour expression of αVβ3 (Sloan et al., 2006). A study has illustrated and showed that, the αVβ3 tumour specific integrin is bone metastatic and over expressing of αVβ3 integrin in MDA-MB-231 cell lines of Chinese hamster are more metastatic to bone when inoculated intravenously than their parental line (Pecheur et al., 2002).
From our results we can conclude that, there is relationship between changes in the number and identity of integrin receptors and alteration of the ability of malignant cells to interact with extracellular matrix in cancer cells. For example, the αVβ3 vitronectin receptor was not present or weakly expressed in normal breast epithelium (Pignatelli et al., 1992).whereas in case of breast tumour cell lines, the more cDNA present in the tumour cells ,the more the αVβ3 integrin is expressed and the higher the density gets.
Since integrins are highly expressed in malignant cells and according to this study, integrins were significantly expressed in different types of breast tumour cell lines as mentioned before, integrin inhibitors are potential target for breast cancer therapeutic. These anti-integrins and antibodies work when receptor clustering is prevented. And the sites to which receptors are attach to ligands are ligated which will induce altered conformational subunit chain(Mizejewski, 1999). For example, MDA-MB-435 cell line has significantly expressed β3 and αV (figure 1C). S247 is an αV β3 antagonist which inhibits the metastasis of expressed αVβ3 in MDA-MB-435 cell line to the bone and that was illustrated by experimental metastasis model which helped suppressing the formation of primary tumour (Harms et al., 2004).Since MDA-MB-231 cell has also expressed αVβ3 integrin according to (figure 2A) and The invasiveness of breast tumour cells is correlated with the expression of αVβ3 integrin(Pignatelli et al., 1992),anti metastatic effect is required however,anti αVβ3 has blocking function by strongly inhibits primary metastatic human breast cancer cells (Felding-Habermann et al., 2001). A recent study has showed that the αV integrin can be recognised by human monoclonal antibody called CNTO 95.Tumour growth of MDA-MB-231 cell line was inhibited by CNTO 95 which means that this antibody has anti-angiogenic effect in breast tumour cells (Chen et al., 2008). Cilengitede is an antagonist of αVβ3 integrin but it's still in clinical trials (Paolillo et al., 2009).
Finally, a conclusion from this presented study is that integrins are cell surface receptors. Their identity and numbers can be altered in case of cancer. Their expression is a significant target for modulating inhibitors and developing antibodies. Further work needed to demonstrate the factors that inhibitors